This invention is directed to surveying an audience to determine whether it is tuned to a given radio station and, more particularly, to a technique which utilizes an apparatus carried on the person of individuals acting as test subjects that is responsive to unique signal transmitted by the selected radio station and automatically stores information indicative of a radio near the test subject being tuned to the radio station of interest.
It is important for a number of reasons to survey an audience to determine to what extent it is tuned at any given time to a particular radio station. Advertisers are, of course, interested in determining the number of people exposed to their broadcast commercials and to characterize their listeners by economic and social categories. Broadcasters find the statistics regarding audience size and type beneficial in setting their advertising rates.
Prior art techniques for obtaining such information involve primarily the following approaches. People within the range of the radio station are contacted by phone and interviewed regarding their listening habits. Each person is questioned about the radio stations which that individual listened to during the previous, say, twenty-four hours. However, this technique is suspect because it is subject to recall errors as well as possible bias introduced by the interviewer. If specific radio stations are mentioned to the person being interviewed, the suggestion may elicit a positive response when tuning to that particular station actually did not occur. Another technique involves keeping diaries by persons agreeing to act as test subjects. Diary entries are to be made throughout the day to keep track of what stations are being listened to. The diaries are collected periodically and analyzed. However, this approach is prone to inaccuracies because the test subjects may fail to make entries due to forgetfullness or laziness. Thus, it can be readily seen that the recall-dependent approach first described above is unsatisfactory because people may not accurately remember what radio station they listened to at any particular time and, also, because of the potential problem of suggestive bias. The diary-based approach is likewise unsatisfactory because people may not cooperate and be as meticulous as required to obtain the desired record-keeping accuracy.